Identification And Function Analysis Of A Promoter With Root Tissue-specific Expression And Drought Resistance Gene In Common Wild Rice(Oryza Rufipogon Griff.)

Rice is one of major food crops around the world.Improving rice varieties through genetically modified technology is one significant method of rice productions of biology-technology breeding.Nowadays,with genetically modified technology of rice developed,the genes of insect resistance,disease resistance,herbicide tolerance,high yield and high-quality rice have been cloned and transferred to the rice varieties.In addition,some of which have completed safety evaluation and entered into productive tests.Pollen-mediated gene flow is one of the most important ways to evaluate the safety of transgenic rice.In this study,we have investigated the differences in the pollen competition of different donators to receptors in the natural state,and found the differences in gene flow of genetically modified rice,in order to establish gene flow model of transgenic rice.Meanwhile,by using cloth to isolate receptors as isolation measures,we have found effective measures to control gene flow.Transgenic rice varieties(B9 and B2)introduced herbicide-resistant bar gene,conventional Indica rice 9311 and Japonica rice Xiushui 63(XS63)were taken as rice pollen donor materials,and sterile line BoA was used as rice pollen receptor.The quantitative and genetic competition of Japonica/Indica rice double pollen donor was studied by using different proportion of pollen donor materials.At the same time,using Indica rice B9 with bar gene resistant to herbicide as rice pollen donors,and conventional rice 9311 as rice pollen receptor to study the effect of isolation mode on rice transgenic flow,The test results mainly included the following points:(1)The quantitative competitiveness of pollen source combinations of the same subspecies is shown by the relationship between gene flow frequency and transgenic pollen donor line ratio in the S curve;under the combined effect of quantity competition and genetic competition,the gene flow frequency of Indica rice is higher than that of Japonica rice,indicating that Indica rice pollen competition is greater than Japonica rice.As a result,the gene flow of rice is influenced by both pollen quantity competition and genetic competition(2)The frequency of gene flow without isolation measures was greater than that with the isolation measures.The gene flow was limited after isolation treatment with cloth,indicating that isolation dramatically reduces the frequency of gene flow.Therefore,setting up physical barriers for rice planting during the flowering period could effectively reduce the probability of cross-pollination and increase seed purity.(3)Under the effect of isolation,the isolation effects in each direction were different.The frequency of gene flow in isolation was about 30%of non-isolation.The isolation effect was significant.(4)Under the condition of setting up 2-meter-high cloth to isolate rice,The gene flow frequency increases gradually with distance,then decreases gradually,and finally approaches zero.With the increase of pollen source distance in all directions,the gene flow frequency decreases.In the low-frequency direction of gene flow,isolation distance over 4 m can effectively prevent pollen diffusion.The key factors for gene flow of transgenic rice research,was that quantifying the frequency of gene flow and controlling or reducing its gene escape.By studying the effects of pollen competition on gene flow,we are likely to more accurately evaluate the occurrence,development,and environmental impact of gene flow in the process of transgenic rice planting,and we can explore more effective isolation measures.It is of great significance for further,objective,comprehensive and accurate study and evaluation of gene flow.